The invention relates to a device for rapid adjustment of microscope stages, using an additional transmission which is arranged between the focusing drive and the stage, and by means of which the stage is lowered or raised a predetermined amount.
Illustratively, such devices are needed to provide a certain safety spacing between the stage (which is vertically adjustable, for focusing) and the objective of the microscope, with the capability, after replacement of the specimen, to move back immediately into the correct working distance. In this connection, it is not necessary that the focal plane of the microscope be precisely reached again; however, it should at least be possible to see an image of the object on which one can focus easily, i.e., without having to seek it.
Such devices facilitate work with specimens of different thickness if the stroke of the rapid adjustment device corresponds to the difference in thickness, from one to the next-successive specimen.
For rapid adjustment of a microscope stage, West German Pat. No. 1,221,031 discloses a device which uses an angle lever which is mounted in the stationary part of the microscope stand. This lever displaces the point of support of a reduction-lever transmission which is arranged between a fine-displacement drive and a separate coarse-displacement drive and thus displaces the stage vertically by a predetermined amount.
However, the device of this German patent cannot be readily used if the focusing drive of the microscope is developed as coaxial coarse and fine drives, with a common driven pinion. Furthermore, it has the disadvantage that the reduction transmission strikes its stop relatively harshly upon lowering via the rapid adjustment lever. This gives rise to vibrations and, in the long term, damages the focusing drive.
Swiss Pat. No. 526,118 discloses two embodiments of another device for the rapid adjustment of microscope stages, both embodiments being interposed between a coaxial coarse-fine drive and a displaceable stage.
In the first embodiment, the device consists of a differential transmission arranged between the driven pinion of the focusing drive and a rack on a stage carrier. Such an intermediate transmission is, however, relatively expensive and increases the price of a thus-equipped microscope.
The second embodiment uses an eccentric which is mounted in the stationary part of the stand and which vertically displaces the pivot point of a lever which connects the focusing-drive rack to the stage carrier. This embodiment has the disadvantage, on the one hand, that it is necessary to provide within the stand two guides whose length extends over the entire range of adjustment of the focusing drive. On the other hand, this lever transmission only operates satisfactorily if the angle of swing of the lever is not too great. This device is therefore not well-suited for focusing drives which have a relatively large stroke since, in such cases, the lever must be made very long, with the result that the distance between the stage and the focusing drive becomes relatively great, and the device itself assumes unwieldy dimensions.